UniCredit SpA is telling investors considering buying shares in the Italian lender’s 7.5 billion- euro ($9.6 billion) rights offer they should weigh the possibility that the euro may be abandoned.

“Concerns that the euro zone sovereign debt crisis could worsen may lead to the reintroduction of national currencies in one or more euro-zone countries or, in particularly dire circumstances, the abandonment of the euro,” UniCredit wrote in its prospectus published yesterday. A euro-area breakup could have “a significant negative impact” on the lender, it wrote.

What began as a Greek deficit problem in 2009 has become a threat to the international financial system amid investor concern that nations including Italy may struggle to repay debt. The breakup of the region’s currency is now “somewhat likely,” said Paul Vrouwes, who helps oversee about 12 billion euros of shares at ING Investment Management in The Hague.

“In the past six months the possibility of a breakup has risen significantly from an event that was not likely,” said Vrouwes. “I expect more companies to add this risk factor” in their offer documents, he said.

UniCredit officials in Milan declined to comment.

UniCredit Chief Executive Officer Federico Ghizzoni told Italian daily Il Sole 24 Ore in an interview published today that the abandonment of the euro is “unrealistic.”

UniCredit is the first of the five publicly traded Italian banks that have sold stock in the past year to list a euro breakup as a potential risk. The bank’s warnings to investors also include the potential deterioration of access to liquidity and the impact of interest rate swings.

Covering Bases

“Even if fairly remote, issuers need to cover all the bases,” said Tom Troubridge, the London-based head of the capital-markets group at PricewaterhouseCoopers LLP.

UniCredit, which owns about 39 billion euros of Italian government bonds, is selling stock to boost capital and meet regulatory requirements for a core Tier 1 capital ratio of 9 percent by June. A group of 26 securities firms led by Bank of America Corp. and Mediobanca SpA have guaranteed the offering.

The debt crisis, now in its third year, saw Italian and Greek bonds post their worst years on record in 2011 as Europe’s financial woes intensified. Greece, the first euro-zone nation to agree a bailout, is still seeking a final agreement to write off at least half of its debts in a so-called private-sector involvement agreement.

Prime Minister Lucas Papademos yesterday told Greeks that cuts in income are the only way to stay in the euro and get more financing from international creditors to avert an economic collapse that may otherwise come as soon as March.

“It makes sense to include a euro breakup as a scenario if the markets into which you’re selling are sensitive to the subject,” said Giovanni Bossi, CEO of Banca Ifis, an Italian financial-services company. Investors in the U.K. and the U.S. “are betting and attacking the euro.”